The Ribavirin Pregnancy Registry: An Interim Analysis of Potential Teratogenicity at the Mid-Point of Enrollment

INTRODUCTION: Significant teratogenic effects have been demonstrated in all animal species exposed to ribavirin. Ribavirin is prescribed for chronic hepatitis C and is contraindicated in women who are pregnant and in the male sexual partners of women who are pregnant. Both sexes are advised to avoid pregnancy for 6 months after exposure. The Ribavirin Pregnancy Registry was established in 2003 to monitor pregnancy exposures to ribavirin for signals of possible human teratogenicity. METHODS: This voluntary registry enrolls pregnant women with prenatal exposure to ribavirin. Exposure is classified as direct—women taking ribavirin during pregnancy or the 6 months prior to conception—or indirect—women exposed through sexual contact, 6 months prior to or during pregnancy, with a man who is taking or has taken ribavirin in the past 6 months. Women are followed until delivery and infants for 1 year. When enrollment is complete, birth defect rates will be compared with the Metropolitan Atlanta Congenital Defects Program’s published rate of 2.67. Using data collected since inception in 2003 through February 2016, preliminary rates were calculated. RESULTS: The registry has enrolled 272 pregnant women, with 180 live births: there were seven birth defect cases among 85 directly exposed women [7/85 (8.2%) (95% confidence interval (CI) 3.4–16.2)] and four birth defect cases among 95 indirectly exposed women [4/95 (4.2%) (95% CI 1.2–10.4)]. Of the 11 infants, nine had structural defects and two had chromosomal anomalies. Patterns suggesting a common etiology or relationship with ribavirin exposure are not seen. CONCLUSION: Based on the patterns of birth defects reported, preliminary findings do not suggest a clear signal of human teratogenicity for ribavirin. However, the current sample size is insufficient for definitive conclusions, and ribavirin exposure should be avoided during pregnancy and during the 6 months prior to pregnancy, in accordance with prescribing information. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00114712.